Automatically-adjusted carbon-arc lamp



March 17, 1931.

A. HJELM AUTOMATICALLY ADJUSTED CARBON ARC LAMP 'JIE Filed Aug. 2 4 1928 s Sheets-Sheet 2 Pap March 17, 1931. A. HJELM 1,796,601

AUTOMATICALLY ADJUSTED CARBON ARC LAMP File Aug. 24, 1928 s Sheets-Sheet 3 a2 J@ E Patented Mar. 17, 1931 stares @FFlCE ALBIN HJ'ELM, OF CHICAGO, ILLINOIS, ASSI ILLINOIS, A CQEEOL TO BRITLSUN, 1110., OF CHICAGO, F ILLIIEGIS Application filed August as,

This invention relates to improvements in an automatically adjusted carbon arc lamp especially for therapeutic purposes, and has for one of its principal objects the provision of means for automatically maintaining the terminals of a pair 01" carbon electrodes at a desired fixed distance from each other, the burning away of the ends of the carbons being compensated for by means of a feed mechanism including a solenoid.

One of the important objects of the invention is to provide a carbon teed mechanism which will movably retain the carbon electrodes in operative position and will reduce vibration of the said caroon electrodes to a minimum.

It is common knowledge among those,

skilled in the art that the magnetic field intensity produced by a solenoid is directly proportional to the current flowing through the solenoid and that consequently the force exerted by the field upon a movable core contained within the solenoid will cause the core to move against a constant resisting force a distance directly proportional to the current flowhg in the solenoid. It is also well known that the relation etween the variation of the length of a carbon arc gap and the variation of the current flowing thereacross is not a linear one. Applicants device accordingly provides means for compensating for this difference of relative movements, namely the linear relationship of the current to the solenoid core movement and the non-linear relationship of the current to the carbon gap length. The said means comprises a combination lever and cam carbon feed mechanism which will smoothly move the carbons together as they burn away eliminating any tendency of the carbons to oscillate or vibrate until an equilibrium is reached, as is the case Where th solenoid core and the carbon move in a linear relation to each other.

A further important object of the invention is to provide an electrically operated damping means for retarding the motion or" the solenoid. core and a manual adjustment for the damping means thereby regulating the length of the arc gap which tends toward Serial Ii 0. 301,780.

tinction the characteristics of the con necting clips heretofore used which expand wh n heated and form an imperfect contact with the carbon.

{Ether and further important objects of the inv ntion will be apparent from the disclosures in the accompanying drawings and following specification.

The invention, in a preferred lustrat d in the drawings, and more fully described.

In the drawings:

Figure 1 is a side elevation, partly in section and parts being broken away, of the improved carbon arc lamp of this invention.

Figure 2 is a front elevation or" the illuminatin unit, illustrating in particular the positioning of the carbons in front of the reflector.

Figure 3 is a rear elevation of he illuminating unit showing particularly the automatic carbon feed mechanism.

Figure 4: is fragmentary side sectional view of the elecrical damping means.

' taken on the form, is il- 1 i hereinafter line o-5 of *igure 4.

Figure 6 is a oetail sectional view of a portion of the feed mechanism, illustrating constructed of a light durable ruetal capable of taking a --ign polish. A bracket 12 is r'veted or bolteo to the lower portion of the reflector and adapted to be adjustably mounted upon a suitable support, not shown in the drawings. The top portion of the reflector is provided with a ventilatin opening 14 and positioned thereabove is a canopy or shield ill to prevent the undesirable escape of the light rays from tne interior. Surmounted upon the rear portion of the reflector 10 is cylindrical cap 18, preferably made of a slightly heavier material than that comprising the reflector casing proper.

flurasly within the casing 10, by means of rgs 20, b shown in Figure 8, and a as, shown Figure l; and adapted to be olteo. o t .e inner sides of the said reflector, is an uminating unit A.

The unit A is preferahy constructed as unitary structure built a ound a frame plate 24, preferably of a light d rable material such as aluminum or the like. it is not essential that this plate be metal but it must present heat resist g qualit es characteristic of a metal. Blted or otherwise suitably fastened to one face of the plate 24 is a reflector plate 26 and inserted therebetwcen is alayer of heat insulating material such as asbestos or the like 28. The purpose of the material 28 is to reduce the heat transfer from the plate 26 to the frame 24 to a 1 iini'mum. Another means for d creasing'this aforementioned heat transfer is the provision of an opening 30 in the ce-iral portion of the plate 24, air, as is well known, being a good heat insulating medium.

Referring particularly to Figures 1 and 2, a pair of carbon clamps 32 is rigidly mounted upon the face of the reflector plate 26, each being adapted to hold a carbon pencil 84. The mounting provided for the clamp 32 comprises metal blockilo upon the face of which is positioned a strip of insulating material 38 such nice. or the like. A screw 40 holds the nember S rigidly in contact with the insulating strip 38 and conse uently retains the block 36 in desired position upon the plate 24. The screw 40 is insulated from both the plates 24- and 26 as is the member 32. Hence a perfect thermionically and electrically insulated electrode is provided for the fixed carbons 34.

A pair of vertically movable carbons 42 is positioned adjacent the fixed carbons 34, the ends of the carbons 42 and 84 abutting, whereupon the carbon arc is adapted to be struck when tie carbons are energized.

The carbons 42 are slidably mounted in a pair of insulating bushings 44, best shown in detail in Fi ure 6, which are in turn idly lBC-Uln ed in a supporting framework 46 fixed upon the plate 24. A clutch 48 is associated with the carbon 34 in such a manner that when the clutch is raised at one side by a connecting link 50, teeth 52, which are rigidly mou--ted in the clutch and positioned on each side of the c rbon, will grip the carbon move the same therewith. The teeth'52 are preferably constructed of some hard insulating material such as lava, tlint or the like.

Pivotally attached to the upper end of the link 50 is one leg of a substantially ll shaped element 54,both legs of which are hown best in Figures 6 and 7. The other leg of the memberv 54 is rigidly mounted up 11 one end of a lever 56 which in turn is pivotally connected to the lower portion of a lug 58 at the point 60. The other end of tee lever 56 is free and rests loosely upon cam 62. Curved faces 63 of the lever 56 co-operate with the cam. One portion of the cam is pivotally mounted upon a support 64 which is ounted on the plate 24. Another portion he cam is pivotally con nected to one end of a link 66, the other end f the said link being pivotally attached to a l ver 68, positioned immed ately above the ever 56. One end of the lever 68 is pivotally mounted upon the upper portion of the lug 58. Hence it is obvious that upon an upward movement of the lever 68, by the suitable cam and lever mechanism, de-

scribed above, the lever 56 and hence the carbons 42 will also raise, but not at the same rate as the actuating lever 68.

Referring particularly to Figures 1 and 3, a pair of solenoids 70 is mounted upon the back of the plate 24 and slidably positioned in the axial center of each magnetic core 72. A flat bar 74 is rigidly attached to and forms an extension of the lower end of the core 72. The bar 7 4 is also constructed of a ma etic metal and is adaptedto slide adjacent the poles of a magnet 76, the said magnet being energized by means of a coil 78, connected in series with the solenoid 70. A strip of non-magnetic material, preferably metal, is positioned between the poles of the magnet 76 and the bar 74 to provide a gap between the two elements and hence decrease the magnetic pull upon the bar. Upon energizing the solenoid 70, the core 72 is moved by means of the magnetic flux set up there n, but the coil'TS being energized at the same time causes a flux to be set up in the magnet 7 6 which in turn attracts the bar 74 and provides a damping means for the motion of the core. A means for varying the damping effectof the magnet 76 upon the bar 74 comprises a pair of set screws 80 and 82, the screw 80 adapted to frictionally engage the'side of the bar 74, the other screw 82 similarly engaging the edge of the said bar.

Rigidly connected to the upper portion of the core 7 2 is anon-magnetic metallic rod 8 lwhich in turn has mounted upon its upper end a strip of resilient metal 86 positioned ri 'htangles to the said rod. The outer end or the strip 86 is rigidly attached to a ll shaped connecting element 88, the other end of which is attached to one end of a second resilient strip 90 parallel to the first strip. The other end of the strip 90 is rigidly mounted upon the lever 68. Thus is that the motion of the core 72 is flexibly transmitted through this above described re silient connection to the combination cam and lever carbon feed mechanism and hence to the movable carbons l2.

The ener Zing current for each set of carbons 34: and a2 and each carbon feed mechanism 70, 72, 68 etc, is brought in through an opening in the cap 18, the said opening being provided with an insulating bushing 92. A duplex lead as is connected at one end to a suitable source of current, such as the house current or the like. The inner end of one of the conductors of the duplex 9 is connected to the screw 40 which, as has been ascribed above, is elect "ically connected to tne clamp 32 and hence to the fixed carbon as. The other conductor of the duplex 9% is conn cted to an insulated binding post 96, the insulation comprising a mica asher or bushing 98. The current is car therefrom to the solenoid 70 by means of a conductor 100, thence to the magnet coil 78 by a conductor 102, through the coil 78 and thence through wire 103 to a terminal 10 i. A bus bar 106 extends from the terminal 10a outwardly through an insulating bushing 108 positioned in an opening in the cap 18. A bead insulated flexible conductor 110 then connects the other end of the bus 106 to a L? shaped clip 112 which irictionally grips the upper end or" the movable carbon Q2.

The clip 112 is constructed of a metal which contracts when heated and hence when the carbon 42 is heated the clip grips the carbon tighter instead or expanding and loosening its grip upon the carbon, as it would it made or the ordinary metal heretotore used on such devices.

A modification of the clip is shown at 11A in Figure 9, the said clip being mounted upon the carbon 4.2 at right-angles to the same, dis inguishine from the clip 112 which clips over the top or the carbon pencil.

One circuit has been described above, but shown best in Figure 3, two such circuits comprise the unit, each being connected as described, but in no way interconnected. Therefore, the device may be operated with a carbon or with double carbons as desired.

It is apparent that herein is provided a device which is flexible, eliicient and possesses extremely rugged characteristics. The device is simple to operate, being practically automatic throughout, the manual adjustments being reduced to a minimum. The device as a whole is constructed with a View particularly to being operated by a person inexperienced and unfamiliar with technical and electrical operations and principles.

I am aware that many changes may be made and numerous details of construction varied throughout a wide range without dcparting from the principles of this inven tion, and l tierefore do not purpose limiting the patent granted hereon otherwise than as necessitated by the prior art.

I claim my invention:

1. In arc lamp, a damper for the carbon feed mechanism comprising a solenoidally operated plunger connected to said feed mechanism, and magnetically operated nping means for said plunger, said magi,

netically operated damping means comprising an elecno-magnet, and an extension on the end of the plunger, the said extension adapted to slide adjacent the poles of the magnet.

2. In an arc lamp, a damper for the carbon feed inechanisn'i comprising a solenoidally operated plunger connected to said feed mechanism, and magnetically operated damping means for said plunger, said magnetically operated damping means comprisino an electromagnet, an extension on the end of the plunger, the said extension adapted to slide adjacent the poles of the magnet, and means for providing a magnetically inactive gap between the poles and the ex tension.

3. In an arc lamp, a damper for the carbon feed mechanism plunger connected to said feed mechanism, and magnetically operated damping means for said plunger, said magnetically operated damping means comprising an electro-magnet, an extension on the end of the plunger, the said extension adapted to slide adjacent the poles of the magnet, and means for providing a magnetically inactive ap between the poles and the extension, said means including a strip of non-magnetic material mounted upon the pole faces.

4. In an arc lamp, a damper for the carbon feed mechanism comprising a solenoidally operated plunger connected to said feed mechanism, and magnetically operated damping means for said plunger, said magnetically operated damping means comprising an electro-magnet, an extension on the end of the plunger, the said extension adapted to slide adjacent the poles of the magnet, and means for providing a magnetically inactive gap between the poles and the extension, said means including a strip o1 non-magnetic material mounted upon the pole faces, and additional means for varying the proximity of the extension and the said non-magnetic strip.

5. In an arc lamp a damper for the carbon feed mechanism comprising a solenoidally operated plunger connected to said feed mechanism, and magnetically operated damping means for said plunger, said magnetically operated damping means comprising an electro-inagnet, an extension on the 10 end of the plung r, the said extension adapted to slide adjacent the poles of the magnet and means for providing a magnetically inactive gap between the poles and the extension, said means including a strip of non-1nagnetic material mounted upon the pole faces, and additional means for .varying the proximity of: the extension and the said non-magnetic strip, said additional means comprising a plurality of set-screws operatively associated with the extension.

In testimony whereof I afiix my signature.

ALBIN HJELM. 

